| 摘要 |
<p>A safety check valve for pressure operated apparatus, in particular presses comprises two axially disposed control pistons movable axially independently of one another in a cylindrical housing having a fluid inlet at one end and an outlet at the other. One of the control pistons has a closed end engageable with a first valve seat surrounding the inlet opening of the housing, an axial bore surrounded by a second valve seat at the opposite end of the piston and at least one radial hole communicating with the axial bore. The other control piston has a closed end engageable with the second valve seat, an axial bore opening at the opposite end of the piston and at least one radial hole. The control pistons are spring biased toward their respective valve seats and are movable against the bias by fluid pressure. With this arrangement either control piston will check the return flow of fluid regardless of the position of the other.</p> |
